[shawnz]

But what do you name the variable in the languages that don't support such a constrained type feature (the majority of them)?

[SideburnsOfDoom]

Object-oriented languages have equivalent constructs, so I would say that this is doable in the vast majority of languages in common use:

https://news.ycombinator.com/item?id=24374372

http://wiki.c2.com/?ValueObject